NAIROBI , Kenya -LRB- CNN -RRB- -- Two U.S. filmmakers were injured Saturday when their small plane crashed into a three-story residential building in downtown Nairobi .

People gather around the wreckage of a plane that struck a building in the Kenyan capital of Nairobi on Saturday .

Dan Parris , 25 , and Rob Lehr , 26 , both from St. Louis , Missouri , were shooting an independent documentary on poverty in Africa .

Both men were hospitalized and expected to survive , according to David Peterka , who was part of the film crew , but was not aboard the plane . He said that all four aboard the plane were Americans .

A flight engineer , whose name was not released , was critically injured and was in a coma , Peterka said . The pilot , whose name has not yet been released , was killed in the crash .

The crew had been in the east African nation for four days and was shooting video of Kibera , one of the largest slums in Africa .

The plane was headed to nearby Wilson Airport , where most light aircraft land in the Kenyan capital .

`` The pilot had warned that he was going to hover and go slow , '' Peterka said . `` They were surprised when they went to about 50 feet off the ground -- and then they hit electrical lines and the plane flipped into the building . ''

Just before the plane crashed , the listening devices went off and they could not communicate with the pilot , Peterka said .

Peterka said Lehr , who was ejected because the doors were open for filming , ran back in to rescue the others . Parris crawled out and Lehr , with the help of bystanders , pulled the pilot and the engineer out as the plane burst into flames , Peterka said .

`` Local residents were using water , dirt to put the fire out '' before the fire department arrived , Peterka said .

`` Before the plane crashed , witnesses said it was flying unusually low , '' said Francis Mwaka , a Kenyan federal communications official .

The four-seater plane was owned by African Inland Missions company .

No one on the ground was injured , Mwaka said . The crash is under investigation .

CNN 's Ben Brumfield contributed to this story .

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Pilot killed , three passengers injured when plane crashes into building

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Two victims were U.S. filmmakers shooting documentary on African poverty

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Dan Parris , Rob Lehr were taken to hospital , expected to survive

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Witnesses say plane was `` flying unusually low '' before crash